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Plant root used to create eco-friendly lithium-ion battery

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December 11, 2012

Researchers have used a dye extracted from the root of the madder plant to develop a new '...

Researchers have used a dye extracted from the root of the madder plant to develop a new 'green' lithium ion battery (Photo: Carstor via Wikimedia Commons)

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Researchers have found an eco-friendly alternative to the metal ores currently favored in the electrodes of lithium-ion batteries. The new non-toxic and sustainable battery uses purpurin, a red/yellow dye extracted from the root of the madder plant that has been used for dying cloth for at least 3,500 years – meaning the substance can simply be grown rather than mined.

Currently, lithium cobalt oxide (LiCoO2) is the material of choice for forming the cathode in Li-ion batteries. However, mining the cobalt and combining it with lithium at high temperatures to form the cathode is an expensive and energy-intensive process.

Couple this with the energy used to extract the cobalt at the recycling stage and Dr. Arava Leela Mohana Reddy from Rice University says that for every kilowatt-hour of energy in a Li-ion battery, production and recycling pumps an estimated 72 kg (159 lb) of carbon dioxide into the atmosphere.

Dr. Reddy, along with Rice University colleagues and researchers from The City College of New York and the U.S. Army Research Laboratory, found that purpurin and other biologically based color molecules offer great potential as a more environmentally friendly alternative. This is due to the carbonyl and hydroxyl groups in the molecules that are adept at passing electrons back and forth.

“These aromatic systems are electron-rich molecules that easily coordinate with lithium,” explained City College Professor of Chemistry, George John.

(1) Pristine purpurin and (2) Chemically lithiated purpurin at a 1:2 ratio

Making the purpurin electrode can be done at room temperature in a simple process which involves dissolving the purpurin in an alcohol solvent and adding lithium salt. After the solution turns from reddish yellow to pink, indicating the salt’s lithium ions have bonded with the purpurin, the solvent can be removed and the electrode is ready.

The team claims the purpurin is less complicated to use than the one or two other organic molecules being examined for use in batteries. Additionally, growing madder or other biomass crops would help remove carbon dioxide from the atmosphere. The resulting batteries would also be non-toxic, making them easier to dispose of.

Using purpurin, with 20 percent carbon added to improve conductivity, the research team built a half-battery cell with a capacity of 90 milliamp hours per gram after 50 charge/discharge cycles.

The researchers are confident their green Li-ion battery will be commercially produced in the next few years. This takes into account the time needed to improve purpurin’s efficiency or find and synthesize similar molecules.

“We can say it is definitely going to happen, and sometime soon, because in this case we are fully aware of the mechanism,” said Professor John.

The team’s research appears in Nature’s online and open access publication, Scientific Reports.

Source: City College of New York, Rice University

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
8 Comments

Is a 90 milliamp hours per gram after 50 charge/discharge cycles good? How does this compare to regular, lithium ion battery?

Lawrence Smallman
12th December, 2012 @ 01:49 am PST

Great ideas just keep on coming ... biodegradable? ... don't have to go to war in Africa or Asia to get some ... sounds promising.

Jansen Estrup
12th December, 2012 @ 08:29 am PST

I wondered too,

0.09mAh/G * 1000/1000 = 90Ah/kg

Not huge, but it's right there with lifepo4 batteries. The positive, is that it's been done in the lab, easily and at room temperature.... so some tweaking could get it much higher.

In the other article (lots of physics stuff)

"The reversible capacity of 90 mAh/g obtained after 50 charge/discharge cycles in purpurin is comparable to conventional inorganic insertion cathodes such as LiCoO2 or LiFePO4 and also with recently studied other organic compounds such as Li2C6O6 and Li2C6H4O45, 21, 22, 23. We believe that the specific capacities and rate capabilities of these low electron conducting organic molecules can be further improved by using specially engineered current collectors reported in reference number 29 and 30. Further, proposed mechanism in Figure 2a and existence of different molecular forms of purpurin are based on detailed NMR, FTIR, UV and XPS studies. Thorough NMR studies on both CLP and ELP molecules at various stages of lithiation process supports the binding of Li+ ions with carbonyls and simultaneously with the nearby hydroxyl groups of purpurin as shown in Figure 2A. It should be noted that purpurin and its lithiated analogues have different levels of CH (sp3) character of the bridgehead carbons. The formation of most favored six membered co-ordination site optimize the lithiation process and further increases the capacity of the purpurin-based electrodes."

So they think they can increase the capacity of this type of electrodes, and that's great news.

tgintz
12th December, 2012 @ 08:30 am PST

There's no mention of the water penalty and amount of land required for the eco-friendly battery. The imaginary threat of CO2 compared to the real threat of scarce clean water seems to cancel out the eco-friendly part. What kind of tilling is required; can it be grown year around; what about the waste organics and the CO2 penalty for that, and so forth?

And if they are eco-friendly wouldn't it be best to find if there is a way to recycle this "natural" product before going on with this?

Viator
12th December, 2012 @ 09:59 am PST

Simple. Look up aquaponics, you save 90% of water and takes up little space

pedrow
12th December, 2012 @ 05:44 pm PST

Compared to any energy-intensive process involving inorganic materials, low temperature industrial processes that involve bio-materials are preferable in almost any case that offer similar product performances. Energy intensive processes are always expensive in that they require vast amounts of energy to reach high temperatures and that if you can make such a process at 50-200 degrees Celsius, economics will tell you to go that way.

That is why such a relatively new area as Biocatalysis is blooming right now, as they seek to build organic catalysts and design industrial processes that can be done with engineered enzymes and proteins at 50-100 degrees Celsius at a rate that meet today's industry standards.

The energy bill will do gown immensely, the materials are recyclable and can be acquired locally. The economics will favour it. It's a win-win situation.

Fretting Freddy the Ferret pressing the Fret
13th December, 2012 @ 09:25 am PST

spinach photo cells, redyelliw "dye" from roots. just cant outdoo ole ma N ... best is to borrow. she only has a multi million year, parallel processor head start....

Walt Stawicki
13th December, 2012 @ 11:20 am PST

No one mentioned growing your own batteries some day. That would be cool!

Tyler LeCouffe
14th December, 2012 @ 10:08 am PST
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